Pulse Width Modulators are widely used and a well-known technique used for various purposes; one of these is conversion of a signal intended for signal transfer.
Patent No. EP0077332, filed on Dec. 28, 1981, discloses a Pulse Width Modulation Decoder, which enables a PWM demodulation to have a full direct current settling within one period of the PWM signal. The requirement for the full settling given the technology disclosed within EP0077332 is that the demodulation circuit is exactly matched to the PWM frequency and thereby gives a requirement of having a PWM modulator, which sampling frequency is stable and non-dependent of the continuous input signal.
Self-oscillating PWM designs are typically challenged by not having a fixed modulation/sampling frequency, the sampling frequency being very dependent on both the frequency components and the amplitude of the continuous input signal, which can lead to harmonic distortion and non-linearity due to channel distortion and lack of synchronization between PWM modulator and demodulator.